Automatically controlling electric motors.



No. 890,144. PATENTED JUNE 9, 1908.

H. w. LEONARD.

AUTOMATICALLY CONTROLLING ELECTRIC MOTORS. APPLICATION FILED JAN. 5, 1903.

i-oi7lsf m. Q alt-01414121 This r eostat UNITED ()FEICE.

HARRY WARD LEONARD, OF BRONXVILLE, NEW YORK.

AUTOIMATICALLY CONTROLLING ELECTRIC MOTORS Specification of Letters Patent.

Patented June 9, 1908.

,(lriginalappllcatlons filed February 6, 1897, Serial No. 622,289, and January 28, 1902, Serial No. 91,677. Divided I and this application filed January 6, 1908. Serial No. 137,804.

To all whom it may concern. I Be it known that I, HARRY W's no Leon- An'n, a citizen of the United States, residing at Bronxville, in the county of \Vestchester and State of New York, have invented a certain new and useful Improvement in Automatically Controlling Electric Motors, of which the following .is a specification.

My invention relates to the control of electric motors and especially to the auto- My invention is also, applicable to the operation from a source of power having a tolerably constant amount of energy at a tolerably constant speed,'of machinery the torque element of the )ower of which may vary very widely, sue as'hois'ts, pumps,

locomotives, etc.

'In-- carryin'g my invention into effect, I employ a rheostat connected in the field circuit of 'adynamo electric machine which sup lies a part or allof the ,energ for the wor ing. motor to be controlled; that is to say, instead of regulating the .working motor directl I regulate its source of energy.

cause to be operated automatically preferably by a small dynamo electric machine whose armature is connected in series with'the dri ing motor for the dynamo electric machine which supplies the energy to the working motor so that as the load on this motor varies and hence the amount of energy taken from the main source is varied, the armature ofthe small dynamo electric machine is caused to rotate an adjustable load or other device and by means of a suitable driving connection the rotation of this armature adjusts the position of the rheostat lever to control the field strength of the dynamo electric machine which supplies the energy to the working motor. Thus it will be seen by this arra elnent I automaticall cause to be varied t a net eflective volts elivered to the working motor to such a voltage as will'operate the motor at the speed required.

My invention is illustrated in the accompanying drawings in which Figure 1 is a diagram illustrating an arran enient inflwhich the armature of the wor ng motoris connected in 'a local circuit in ser es With the armature of'a-dynamo-g.

electric machine, the .fieldstrength of-which-H is controlled by the automatic device which responds to variations in the amount ,of energy taken from the main line by the machine which drives this generator; and 2 is a diagram showing an application of my invention to the operation of a. moving vehicle.

Referring to circuit extending therefrom.

C is a dynamo electric machine driven by motor 0' andD 'is the working motor connected in the local circuit 13-14 extending from the armature terminals of machine C. The field windings of U and Dare connected directl across the main line 12 and the field win ing of machine (3 is also connected across the main line but in series with a rheostat R. The contact lever of this rheostat is operated b means of the worm ear n or other suitable means driven by a s aft extending from the armature of a small dynamo electric machine N. On this shaft is a hub to which is connected an adustable spring or equivalent adjustable loading device n. The armature of machine N is connected in series with the armature of ma chine C across the main line l 2 and the field of machine N is wound to be connected directl across the main line. The-armature 0 machine N is of low voltage and the current foranachine C passing through that.

armature produces a torque in the armature.

the drawing, 'B re' resents a mam source of electr c energy an 12 the of machine N which is balanced by the .ad-

justable device n. Thus it will be seen that if the current to machine (3 becomes too large, due to a decrease of speed an,-' counters electromotiye force of C' with re-.erence to the electro-motive force of the supply circuit, the torque of machine N causes its shaft to revolve and tln-ou n the worm gear n adjust the rheostat R to cause a drop in the voltage a of machine C and hence a reduction of the electro-motive force at the terminals of the 5 working motor D.. When the current to ma. chine 0' falls, the spring or equivalent device connected with the armature shaft of machine N causes that shaft to rotate in the opposite direction thereby re-adj usting the rheostat R to-causc an increase in the vol tage of machine 0 and hence an increase of the electro-motive force at the armature ter- -1-ninals of the working motor. Thus it will be noted that the action'of motor N is depcnd- .15 ent upon the relative values of the two electro-motive forces in its circuit, which are the practically constant electro-motiveforce of the supply circuit and the relatively variable opposing -or counter electro-motive force of t e motor C.

The dynamo electric generator 0' which su plies energy to the armature of motor D w'l supply a'current dependent upon"the torque required of D-which torque--'will in many practical instances vary over'a' wide range. When the torque"'requiredabf d) varies, the current generated by C will-correspondingly vary and this will cause a varia tron momentarily in the current flowing 80 through N, on account of the increased work momentarily-performed by C,.which consequently W automatically move R to such a point that the volts generated by C will be such as to. make the watts-supplied to the 85 armature D ractically constant. 'It will be noted thatt e watts of and 'C! are practically equal at all times, and since the power of Cfis practically constant,- being supplied with a constant current at a constant e ectro 40 motive force, the watts of C are also prac' i tically-constant and the watts supplied to the armature of D are alsoautomatically maintained ractically constant, even under conditions oi wide variations of the torque of therworkperfo'rmed' by D This arrange ment is very useful with a workin motor whose torque varies and where it is esirable to always take 'ap roxima'tely the same amount of energy. ith this arrangement applied to a vehicle, for instance, the vehicle would travel fast 'on a level and slow on grades while using the same amount of en- T ig. 2 illustrates one application. of my in- 'vention. The source B is shown connected to the supply and return conductors 1,2 and the car or moving vehicle is indicated at V.

Sliding contacts 8 are shown engaging the conductorsl, 2 and the apparatus on the ve- 0 hicle is similar and corresponds to that shown and described with reference to Fig. l, D representing a propelling motor.

- This application is a division from my aplication anuarv 6. 1903. and from my pending applior Patent No. 717,584, granted cation SorialNo. 91,577, ilcd January 28 Hill). 1

While 1 have only shown one specific form of my invention, the sameis susceptible of many embodiments, and I do not wish or intend to be limited otherwise than as expressed in the following claims.

What I claim is:-

1. The combination with a main source of electric energy, a motor to be controlled, a dynamo electric machinesupplying energy to said motor, a second motor operated by energy from the main source for driving said d fynamo,and means controlled by the amount 0 energy taken by said second motor from an the main source for changing the resistance in one element of said dynamo elcctricnnv chine. x

The-combination with a main source of electric energy, a motor to be controlled, at dynamo electric machine, supplying energy to said motor;a,second motor operated by energy from the'main' source for r riving said d ratio, and means controlled by the amoi'mt 0 energy taken: by said second motor from 0 the mainfsource Torcontrolhng the field excitationioFsaiid dynamo to vary the energy supplied-to the motor to be controlled.

3. "The combination with 'a' mainsource of electric-energy,"afniotor to be controlled, a 5 dynamo electric .maehine supplying energy to said motor, a,second' motor o narrated by energy from the main source for driving said dynamo, and" an electro-re'sponsive device controlled by the amount of energy taken by 00 said second motor from the main source for controlling the energy delivered to the motor to be controlled.- I

v 4. .The cpmbination with a main source of electric energ' a motor to becontrollcd, a dynamo ,electric machine supplying energy to said motor, la second motor ou-ratcd by energy from the main source for l riving, said dynamo,-'and an electro-responsivc device controlled by tl 1e amount of energy taken by 1 said second motor from the ma'in source for, controlling the field-excitation ofsaid dyname to 'vary the energy supplied to the mo tor to be controlled."

'5. The combination with a main source of electric energy, a motor to be controlled, atdynamo' electric machine supplying energy to said motor,--a second'motor o erated by energy from the main source for rivin'g said dynamo, a rheostat forregulating the field of said dynamo, and an; electro-responsive device for operating said rheostat, said'device. being connected in series with the armature of the second motor.'-

6. The combination with a main source of 1?!) electric energy, a momma be controlled, a dynamo electric machine supplying enerr' to said motor, a-second motor 0 rated ig' energy from the main source for rivi'ngsaid dynamo, a rheostat for regulating the field to said motor, a second motor erated y.

energy from the main source for riving said ,1 dynamo, a rheostat forrcgulatirig the field of i said dynamo, and a motor for operating said -rl1eostat, the armature of saidmotor being connected in series with the armature of the second motor..

8 The combination with a main source of 1 ,lectric energy, a motor to be controlled, a dynamo electric machine supplying ener y to. said motor, asecond'rn otor o erated by energy from the main source for riving said.

20. dynamo, a rheostat for regulating the field of said dynamo, a motor for operating said rheostat, and an adjustable load on the armature shaft of said motor, the torque 'of which is varied -in proportion to the en'erg taken from the main source by said 566011 4 motor. 9. The combination with Ii niainisource of electric energy, a motor ll:- be controlled, 'a dynamo electric machine supplying ener y to said motor, a second motor operated y' i 3 energy from the map source forriving said i lating the field of said dynamo, a motor or operating saide ,dynamo, a rheostat' or re rheostat and ha ving its armature connected inseries withthe armature of the second mo 95 tor, and' anrgldjustableload on the armature shaft of the'rheostat motor.

- 10. The combination of a generator normally producing an electro-motive force and sup-plying. energyto a translating device re- 40 quiringa current 'variable over a wide range to; suit conditions of practice, and means dependent u on the current supplied to the ,translating evice for automatically varying thevolts supplied to the'translating deviceby f the generator, so that the watts supplied to the translating device will be practically constanta, 1

11 The combination 'of a dynamo electric generator supplyin energy to an electroniotor, the torque 0 which under conditions of practice varies over a wide range, and means, controlled by variations in the torque of the motorfor'automatically varying the eleotro-mo tive force of the watts of the motor, soas to maintain said watts of the motor practically constant.

12. The combination with a main source of electric energy, a motor to be controlled, a

dynamo electric machinesupplying energy V so to said motor, a second motor operated by energy from the main source for 1 riving said dynamo, and means controlled by he amount of energy taken by said second motor from the main source for delivering to themotonsubstan tially the same amount of energy as that taken from the line at the current re uired 'to operate the motor.

13. he combination of a generator norsupplying energy to a translating device rcquiring a current variable over a wide range tosuit conditions'of practice, and means ex ternal to said generator dependent upon the .culrren't sup lied to the translating device for automatical y varying the volts supplied to the translating device by the generator, so that the "watts supplied tothe translating device will remain limits 7 v 14. The combination of- 'a' dynamo electric'mac'hine, an electric motor supplied with ener mally producing an electromotive force and within predetermined therefrom, the'torque of said m'otor varying over a wide range under conditions inlotor within predetermined limits.-

15. In a'gs stem of electric power trans- .force of the generator armature 'as'anin creased or decreased torque outputisde ade- 10o" motive force and a correspondingincrease manded by-"the motor, thereby causing crease or increase respectively of the e ectroof practice, and'means external to said machine dependent upon the torque of the motor required in practice'forautomatically varyg ing the' electromotive"forceof the watts ofthel'motor so jas'itoykeep ther -wattsof the f Q mission,'an" e ectric generator and a suitable motor for operating same, an electric motor whose armatureis supplied {with current from the-armature ofs'aid generaton'and rii'eans exterior. of" the generator acting automaticaliy 'foi controlling'the eleetrcmotive' soui'ce of electric energy means propelled vehicle, 4

pendent up'on the torque required of the rothe energy delivered to the ropelling motor.

17. The combination wit a dynamo electric machine, a circuit supplied thereby, a rheostat arranged to vary the field excitation-of the dynamo electric machine, an electric mctorfor actuating the rheostat, a cir- -cuit in which said motor is connected, and two devices. producing relatively variable electromotive forces in said motor circuit. 18. The combination of a dynamo electric machine, a circuit supplied thereby, an electric motive device for varying the field excitation ofthe machine, a circuit in which said motive device is connected, and two devices producing relatively variable electromotive forces in the circuit of said motive device. 19. Thecombination of a dynamo electric machine, a device for causing a variation in tric motive device operatively' connected thereto, a circuit in whichsaid motive device,

pelling motor for automatically-'contro 'ng' lief the field excitation of the machine, an elecsaid relation.

is connected, and two devices producing normally opposing electromotive forces in the circuit of said motive device. I

20. The combination of an electromotivc force producing device, and a device producing an opposingelectromotivc force in circult therewith, a translating device, and means responsive to a dill'erence between the electroinotive forcesproduced by said de:

vices for controlling the amount of energy de ivered 'to said translating device. j v.

'1. A source of constant clectromotive force, a circuit leading therefrom containing a eountergelectromotivc force producing device, and means responsive. to the difference betweenthe electromotive force of the source and. the counter electroniotive force for controlli the energy delivered.

22. vices, the electromotive forces of which normally have a nearly fixed relation .to cacl 1 other, and means responsive to"'a chang'e' in said relative valuefor coiitrollingone of the;

' to restore;

said electroniotive forces so, as-

'23. A circuit remaining two opposing electromotive force producingfdevicesfand means responsive tothe change in the differ;

ence between thesaidelectrOmot-ive forces for automatically Icorrectmg changes from said diflerence.- 24. A circuit containing two opposing electromotive force producing devices, and

means in said circuit responsive to a change in the difference between the said electrometive forces for iadtoinatically correcting changes from said difl'erence.

2.5. A circuit. containing anelectromotivc I force producing device having a constant clectroinotive force, and also ('ontnining a dc vice having a counter clect-roniotive force which is normally substantially upuil to the constant electromotive force am which is subject to va'riationfin practice, and means included in said circuit responsive to said change in electromotive force for autoinatic-, ally correcting saidchange.

26. A source of electroinotiye force, a circuit leading therefrom, a second circuit, the energy in which is derived froipthe first cir- T cuit, and means responsive to a change of enof an pl an electrically Heft ergy occurring in said derived circuit for restoring the watts of energy in tl cuit'to its normal value.

27. An electrically propelled vehicle, a propelling motor therefor, a circuit including at least one element of said pro pellmg ,motor,

am} automatically movable'ineanson the vehic a dependent uponthe torquerequi'red of the propelling" motor which automatically .governs the watts supplied for the propulsion of the vehicle. Y

28. A constant electroinotive force source cm, a propelling supp energy there wo electroinotive force producing def-- ie derived eirplropelled vehicle liicle responsive to one element of the watts of thetransformed energy for automatically said transformed energy. '1

an ele'ctroniotive. force by magnetic induc-. tion which suppliesIenergy to said translating- .in which produee amiiiipressed-and a counter electromotive fQQOQyLhQ yalues of which electroino ti ve forces. rei'iormally fixed relatively to each 0 l r, anielectroaresponsivedevice ,in

motive force supplied to said vice.

supplying cnergy to a translatingllevice q'nirnig a current var ableover-a;widerang automatica din1in isl|cd.

generator supplyingenergy to an electric mopractice-varics ovcralarge range, and n'ieans icallyinversely varying the. electromotive force 'of tliewatts of the motor, whereby the electrical energy will be transformed into .useful work without material loss' of energy.

tiee varies over a wide range, a dynamo elecfor automatically controllin the currentin rying the volts and am pcrcs supplied to the motor armature.

34. In an electricallyipropelled vehicle, the

tor, of means on vehicle dependent upon "ornied energy, and means carried by the ve- 30. Atranslatingdevice,adevice producing i 3 1. The combination -of. a fgenerator noro}: n ally producingfanelectromot ve force and;-

to suit conditions ofepractice, and means-e1 1; ternnl to said generatordepei dent upongthe, 10,01 current supplied-to the translatingdevice or -I ly. varyiiig thevolts suppliedto .the trimslatingdevice by thegenerator, so that'as the amperes increase the volts will be 32. The combination of a dynamo ,electric tor, the torque otwhich under conditions of trio machine having a field winding energiaed by a current other than its armature current, 129, means dependent upon the current supplied combination withthe electric propelling mothe torque rcquiredol' the jn-olpellinginotor for automatically controlling t 1e energy 110- i3),

is, procontrollin the other element of the watts of 0 device, a circuit and devices connected there- 5 .said circu t vhicliyespondsto achange in-th' J relative va ues ofithe' said two electroinotive.- forces and whiclrtliereby, affects theelect'rdwl,

translating 'des ill external to said generator controlled byvari- 11 v ations hi the torque of the motor for aut0inat 11's I 33. he combination of an electric motor, the torque of which under conditions of prac- H said field winding and ,there iyinversely va-.

l hvered to the propelling motor, said means comprising an clectro-magnetlc winding enthe torque required. of the ergized independently of';.the source supplying the armature of the propelling motor.

35. In an electrically propelled vehicle, the combination with the electric propelling niotor, of means on the vehicle dependent upon pro ielling motor for automatically controlling t e energy delivered to the propellin motor, said means comprising a (1 name electric machine having a field win ing excited independently of its armature current or voltage.

36. In an electricall propelled vehicle, the combination wit-h t e electric )ropelling motor, of means on the vehicle ependent upon the torque required of the propelling motor for automatically controlling the energy delivered to the propelling motor, said means comprising mechanism automatically moved in response to a change of torque of the motor.

37. In an electrically propelled vehicle, the combination with the electric ropelling motor; of means on the vehicle ependent upon the torque required of the propelling motor for automatically controlling the energy delivered to thepropellirig motor, said means comprising a dynamo electric machine having an automatically controlled rheostat for varyin its field strength.

38. In an electricall Y propelled vehicle,

the combination with t 1e electric propelling motor, of means on the vehicle (ependent upon the torque required of the propelling motor for automatically. controlling the energy delivered'to the propelling motor, said means comprising a dynamo electric machine and a n'iovablo element for controlling the strength of its magnetic lield.

Q39. T he combination of a source of electrical energy, one component of which is suh stantially constant and the other of which is variable, a translating device, and electroresponsive means responsive to a change in said variable energy component for maintaining a practically constant supply of energy to said translating device.

40. The combination of a source of electrical energy, both components of which are variable over a vsidc range. :1 motor whose armature is supplied from said source, and means exterior in the motor and said source responsive to a change in one componentof the energy supplied for invcrselv varying the other component of the energy.

41. The combination of 11 source of electrical energy, both components of which are "dynamo, .dynamo for automatically controlling the energy. supplied according to the demand of 100 42. The combination of a dynamo electric generator, and electrically controlled mechanism for varying inversely over a wide range the volts and amperes of said enerator, said mechanism being automa-ticzfily responsive to a change in one component of the energy delivered by said generator.

43. A source of electromotive force, an electrically propelled vehicle supplied with energy therefrom, a propelling motor, a transformer of electric energycarricd by the vehicle, at least one element of the pro elling motor being supplied with such trans ormed energy, an means moving with the vehicle responsive to one element of the watts of the transformed energy for automatically controlling the other element of the watts of said transformed energy.

44. In a vehicle, the combination with a 'rnotor,-of a dynamo, and means external to' 35 said dynamo for automatically controlling the energy of the dynamo according to the demand ofthe motorysubstantiallyas described. 4 r i 45, In a vehicle, the combination with a motor, a dynamo and means for driving the dynamo'g'of'means external to said dynamo for automatically controlling the energy generated according-to the demand ofthe motor, substantially asdescribed 46."--In avehicl'e, the-combination with a motor, a dynamo and means for driving the of electric means external to said the motor, substantially as described.

-47. The combination of a stationary source of electric energy, mains of substau-' tially constant electromotive'force' extending therefrom, a vehicle, a propelling electric motor, means for receiving electric energy from said source and for transforming said energy by magnetic induction and delivering the transformed encrgv to at least one element of saidmotor, and means responsive to a change in the energ, delivered to said clement for'automaticall controlling the amount of energy from said source.

48. The combination of a stationary source of electric energy, mains of substantially constant electromotive force extending therefrom, a vehicle, a propelling motor therefor, moving contact-s'for leading energy upon said vehicle, electro-magnctie means on the vehicle for receiving theencrgy and delive-ring energy to at least one element of the propelling motor, said means comprising an electromagnetic winding connected in alocal loop with said .element of the propelling motor, and means on the vehicle for autei-natie- 2 ally controlling the energy taken from the source according to variation in-the torque of the propelling motor;

49. The oombinat' 31] offer someepf elec-itric energy, a motor generator, theniotor of l3i which has at least one of its windings supplied with current from saidsource, and a device in the path of said current for automatically controlling the current taken from said source for maintaining said current within a predetermined limit.

thework, a'variable voltagegenerator, the armature of said generator supplying'current of said" motorgean electric.

' w ch drives the movable element of said generator, a

to the armature motor, the movable element of.

supply circuit for sup(plyingi e rg'y-to said last nan1ed5m0tor, an

. automatically controlling the current taken from said suppl circuit.

the, electric energy taken fromsaid supply tage, avariable speed and variable torque formed energy;--a

ply circuit for supplying energy electricg. -motor su plied with said transmaintaining the energy taken froi n said supply circuit constant within limits.

53. The combination of an electric motor, the movable element of which is adapted to produce a Widely varying torque and a widely varying speed, a supply circuit, a motorgenerator for receiving energy from said supply circuit and supplying energy to said motor, and automatic means for causing said motor to produce the maximum torque and the maximum speed without exceeding a certain amount of energy from said supply circuit, said means comprising a device in circuit with the energy conducting means between said supply circuit and the motor portion of said motor generator. 1 i

54. The combination of a motor having a separ." 'ely excited lield winding, a generator having a separately excited lield winding, the generator armature being connected in :ircuit with the motor armature, a motor for driving the armature u? the generator, a supto said last named motor, and means lietween said supply circuit and said last named motor for automatically controlling the energy taken from said supply circuit...

55 The combination of a supply circuit of mean between said supply circuit and thelastnamed'm'otor for J circuit into electric' energy ofvariable current and variable vol-;

means for automatically constant electromotive' force, a motor having a winding supplied with and means comprising a centre ling winding in series with said motor winding for automatically Jimiting the-amount of current which can betaken by said winding from said circuit; v "1 56. The combination of a yariable speed generator having a variable torque motor, a winding supplying ener justable means for varying the'voltage and current delivered by said generator winding, a motor for driving said generator, a source of supply for said driving motor, and automatic electroresponsive controlling means for automatically regulating thecurrent fromsaid source for keeping said current within certain limits. I

r 57. In combination, an electricgenerator, a generator circuit, and acontrolling device I for said generator including electroresponsive means operative at a predetermined maxigenelator irrespective of murnloadupon the the valu'eiof current 58. 'The coinbinatl'o by energy therefrom and having a field winding energized independently of its armature current, a rheostat for automatically controlling the operation ofsaidmotor, said rheostat being acted upon" bya constantl .acting force tending to move the same in one irection, and auton 1aticallyresponsive: electromagnetic means for overpowering said force under certain conditions and for moving said :rheostat in the opposite direction, said electromagnetic means being controlled by a current automatically the motor. v

59. The combination of a shunt wound electric motor, an automatic device comprising movable contacts, said contacts being in series with the. motor armature and carrying the motor armature current, and a rheostat automatically controlled bv said device.

(H). The combination of an electric motor,

and means for automatically controlling the operation of the motor and automatically responsive to the. work done by the motor, said means comprising a device in series ith the armature current of said motor and an automatic rheostat controlled by said device.

(H. The method of 0 relating an electrically propelled vehicle w crating electric .energy at substantially constant eleetromotive force at ,a stationary source, transmitting electric energy by conduetors to the vehicle, leading the energy upon the vehicle, transforming theenergy, and employing part of the energy led to the vehicle for inversely varying the voltage of the transformed energy as the ampere-s are varied accordance with the variation in torque of the propelling motor.

iich consists in gen-- encrgv therefrom,

to said motor, ad-

n' ofra constant electro motive pply clrcuit, aniotor operated responsive to the work done by 

